Story highlights

For the first time, it's available on Sprint as well as AT&T and Verizon

Apple on Tuesday unveiled the iPhone 4S, a faster version of its best-selling smartphone that includes a virtual "personal assistant" you can talk to.

"When you think about it, only Apple could make such amazing software, hardware and services and bring them together into such a powerful yet integrated experience," the company's new CEO Tim Cook said at a press conference Tuesday at the company's headquarters in Cupertino, California.

The next-generation iPhone also will be available on Sprint's wireless network for the first time, in addition to AT&T and Verizon. A model with 16 GB of storage starts at $200 with a two-year wireless contract; the 64 GB model costs $400.

An online presale for the phone begins on Friday, and the phone will become available in stores on October 14.

Steve Jobs, the Apple co-founder who recently resigned as CEO amid health concerns, did not take the stage at the press conference and was not seen by CNN reporters at the event.

The iPhone 4S looks identical to a previous model, but it contains an A5 processor that the company says is up to seven times faster at rendering graphics and twice as fast at processing data.

It has a personal assistant called "Siri," which takes voice commands and can translate speech into text.

"I've been in the AI (artificial intelligence) field a long time. This blows me away," Apple's Scott Forstall, a senior vice president for iPhone software, said after he announced the new service, which only works on the iPhone 4S, not on previous models.

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Apple unveils iPhone 4S

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Siri: Apple's new voice recognition

In a demo, Forstall asked the phone to "find me a Greek restaurant in Palo Alto." The phone pulled up restaurants from the app Yelp and said: "I have found 14 Greek restaurants; five of them are in Palo Alto. I have listed them according to ranking."

Some people who followed the event online joked that Siri reminded them of the computer HAL from the movie, "2001: A Space Odyssey."

"We are clearly headed to Terminator/HAL territory here. Humans are doomed. Deal with it," wrote Sam Grobart on the New York Times' live blog of the press conference.

The voice feature also pulls data from Wikipedia and search engine WolframAlpha, among other information services.

The iPhone 4S is also a "world phone," meaning it will be able to place calls more easily on wireless networks all over the world, not just in the United States.

Among the other updates:

-- The phone also has "fantastic battery life," allowing people to talk for eight hours before needing to charge it again, said Phil Schiller, Apple's vice-president for product marketing.

-- It features an 8-megapixel camera with a better light sensor, making it as good or better than many point-and-shoot devices.

-- It will shoot high-definition video, and it has a new image stabilization feature to make YouTube videos less shaky.

Despite some new features, however, some market analysts were disappointed that Apple did not release a more radically designed version of its smartphone, as CNNMoney reports. Apple's shares sagged slightly for the day on news of the phone's update.

At the event on Tuesday, Apple also announced updates to its mobile operating system, called iOS5, which will be available for free on October 12.

The new version of the operating system works on the iPhone 4 and 3GS, as well as both versions of the iPad and the iPod Touch.

The iOS 5 system includes several new features, including a cloud service that will sync some photos and files from the iPhone onto Internet servers. A product called iTunes Match will sync music from the iPhone with a database in the cloud, making it possible to play your music on any device or computer instead of just on the one where you purchased it.

The iTunes Match product will be available later this month, the company said, and costs $25 per year.

A new app called Cards will let iPhone owners send paper greeting cards to people for a fee that includes postage. And, finally, a new social networking app called Find My Friends lets users share their current location with close contacts.

In all, Apple says it has sold 250 million gadgets that run on its mobile operating system.

The company finds itself as the top mobile gadget maker.

The iPhone 4 and the iPhone 3GS were the best-selling smartphone models in the United States in the second quarter of this fiscal year, according to data from the NPD Group. Apple says it sold more than 20 million iPhones in the last financial quarter alone, up 142% from that same period of time in 2010.

Cook on Tuesday said the iPhone is the bestselling phone in the world.

We'll have to wait a few weeks to see how well the iPhone 4S continues that success.